Low water alarm



NOV. 17, 1931. F M RQBY 1,831,884

LOW WATER ALARM Filed Oct. 11, 1929 2 Sheets-Sheet 1 Nov. 17, 1931.

F. M. ROBY LOW WATER ALARM Filed 001:. 11. 1929 2 Sheets-Sheet 2 Patented Nov. 17, 1931 UNITED STATES FRANK M. BODY, OF CLEVELAND, OHIO LOW WATER ALARM Application filed October 11, 1929. Serial No. 398,867.

This invention relates to low water alarms and more particularly to low water alarms for locomotive boilers, and of the type where in the alarm is controlled by the water level in the boiler exclusive of other variations, as

for example, fire-box temperatures.

An alarm of this type is described in detail in U. S. Patent No. 1,684,897, issued September 18, 1928 to Herman B. Thurston. Briefly,

the apparatus disclosed in this patent comprises a reservoir disposed outside of a boiler and above the normal level of the water therein. A tube, terminating at the low water level, connects the reservoir and the boiler in such manner that water will be forced through the tube and into the reservoir by the steam pressure within the boiler. Inside of the reservoir a float is provided which controls a valve and a whistle signal.

\Vhen the water in the boiler falls and remains below the level of the end of the tube,

the water in the reservoir will flow out though not necessarily limited to use with such arrangements.

so The principal object of the invention is to provide a low water alarm which may be easily inspected and which may be cleaned, as by washing out, without danger of injuring the mechanism of the alarm. Another object is the provision of a convenient device for testing the alarm. A further object is the provision of a low water alarm which may be effectively mounted on boilers of different design without change, and which will op erate as well with one as with another.

of locomotives, a low water alarm'for useon locomotive boilers must be rugged, must be easily accessible for cleaning, testing and inspection, and must be sensitive to such an extent as to insure that it will function whenever continued low water requires it. A satisfactory alarm should moreover operate only when the low water condition obtains for some time, inasmuch as actual low water enlarged cross section taken through the. re- Because of the severe operating conditions conditions at the crown sheet occur temporarily when the water in the boiler surges due for instance, to sudden stopping of the locomotive. Y

A further desirable feature of a low water alarm is that one model of the alarm will fit a large number of boiler shapes and sizes. A satisfactory alarm moreover, is not affected by the usual boiler and/or fire box temperatures and boiler pressure changes, as are fusible element alarms such as now used to a large extent on locomotive boilers. Moreover, a satisfactory alarm should be at all times com paratively free from scale and sludge, and provision should be made for easily washing out any scale or sludge accumulation which mayexist; a certainamount of course being inevitable in connection with a boiler which is charged with water varying greatly in sludge forming properties andicorrosiveeffects.

An alarm designed in accordance with the present invention has all the desirable features above discussed as will be hereinafter shown. Other objects and advantages of the invention will appear from the following .de scription thereof, in connection with the accompanying drawings.

Referring briefly to the drawings, Fig. 1 1s a cross sectional view of a locomotive boiler, showing thepreferred embodiment of the apparatus mounted thereon; Fig. 2 is a side elevation of the apparatus, as mounted on a boiler; Fig.3 is a cross sectional view taken substantially along the line 33 of Fig. 2, Fig. 4 is a longitudinal sectional view taken through the apparatus; Fig. 5 is a cross sectional detail on an enlarged scale taken through the controlvalve and Fig. 6 is an movable inspection plug.

In the drawings, A indicates a boilerhaving a roof sheet B, a fire boX- C and crown sheet" D. The steam space of the boiler is shown diagrammatically at S and the water at WV. The line WV may indicate the water level when there is danger shortly thereafter of the water uncovering the crown sheet and allowing it to buckle or be damaged by the intense heat of the fire. i

The principal parts of the alarm, as shown in the drawings, are the chamber or reservoir forming body 1, and which is preferably a hollow steel casting shaped to provide for considerable vertical movement of a float 2 therein, shown as mounted on a float arm 3 which is in turn carried by an inwardly extending bracket 4 on an end closure member 5 forming an end wall of the float chamber. The position of the arm 3 controls the operation of a valve which leads to a suitable signal and which will be hereinafter more fully described, the signal, as illustrated, being mounted on the closure .member 5. Extending from within the float chamber through the bottom wall of the bottom 1 and through the roof sheet of the boiler, is an inclined tube 6 which is open at both ends and which serves to admit water from the boiler to the float chamber to raise the float, and thus, under normal operating conditions of the boiler, hold the alarm signal against operation.

The above described parts are preferably supported on the boiler shell or roof sheet slightly ahead of the rear tube sheet (not shown) and the manner of mounting the body 1 on the boiler comprises, preferably, the provision of a hollow body extension 10 which carries within it the tube 6, and which has adjacent thereto a soft metal ring 11, preferably bronze, the ring having a rounded bottom surface fitting into the slightly chamfered opening 12 in the roof sheet. The rounded surface of the ring member 11 is tightly seated in the opening 12 by reason of a suitable number of attaching studs 14 which are shown as threaded into the roof sheet and which extend through suitably placed ears 15 on the body 1. The studs 14: may be provided with nuts 16 which are drawn down tightly onto the cars.

This arrangement of mounting prevents any possibility of steam leakage, into the atmosphere, since the material of the ring is non-porous and soft enough to fit into any depressions in the seat at the opening 12 when borne down by the attaching stud nuts. The relatively soft metal of the ring forms the same sort of seal where thering contacts with the body extension 10. It will be seen that irrespective of considerable variation in inclination of the boiler shell portion to which the apparatus is attached, the float, by reason of the body mounting described, may be made to move in a vertical plane about its pivot, this being obviously desirable, if not essential.

The water inlet and drain tube 6 comprises, as shown, a short sleeve 21, preferably bronze, which is threaded as at 22 into the interior of the extension 10. The sleeve has suitably secured thereto as by the usual threaded connection, a light tube or drop pipe 23. This is preferably copper for corrosion resistance. Rising upwardly from the sleeve 21 and shown as formed as a separate part is an inner pipe 25 (Fig. 3) which, as shown, is threaded into the top of the sleeve.

The pipe 25 extends to nearly the top of the float chamber where it is open, to freely discharge water into the chamber, and preferably provided with end notches 26 to provide for the removal and replacement of the inner pipe as with a tool similar to a screw driver.

The sleeve 21 is provided with a drain opening at 21 (Fig. 3), to allow the water to drain out of the float chamber, under low water conditions in the boiler, at a comparatively slow rate, so that the alarm will not be actuated during temporary but not dangerous low water conditions.

The tube 6, as a whole, is arranged to be inserted through an opening 30 in the top of the reservoir casting, the opening being fitted with a bushing 31, preferably steel, and welded in place, the bushing being closed by a removable inspection plug 33 adapted to be taken out and replaced as by means of a wrench. All the parts of the tube may be assembled into place and removed from the apparatus through the inspection opening in the bushing 31.

The plug 33 has coarse squared threads so as to prevent the plug from being cross threaded into the bushing, and above the threads, the plug has a rounded shoulder surface 35 which is adapted to engage a conical surface 36 of the bushing, for forming a tight seal.

Embracing the inner pipe 25 and resting on the sleeve 21 is a hollow spider member 40 which is provided with circumferentially spaced wings ll at its upper edge, closely adjacent the opening in the bushing 31 which receives the plug. The overall diameter of the spider is slightly less than the inside diameter of the bushing 31. The purpose of the wings is to provide for closing the plug opening against the entrance of a nozzle, such as used on the usual hose for cleaning sludge and scale from the interior of boiler parts,

while permitting cleaning liquid to be forcibly injected into the chamber from such a nozzle to clean out the sludge and scale. It will be understood that this method of cleaning out is only used where water conditions result in scale deposits or excessive sludge,

since I have provided for .a more readily practiced method of blowing out the alarm by steam and boiler water, the apparatus for which will be presently described.

The advantage of the wing formations on the spider member 410 will best be appreciated with relation to the float arrangement. It is obviously highly essential that the float operate freely. If the insertion of the cleaner hose nozzle were permitted, it might easily damage "the float or cause it to bind against the inside of the body casting.

By way of providing against'removing the spider when flushing out the float chamber,

" as above discussed, the axis of the inspection plug bushing 31 is eccentric to the axis of the pipe 6 and spider. The eccentricity is totricity mentioned prevents the easy removal of the spider because the bushingoverhangs the wings of the spider at the side thereof toward the attached end of the float arm.

When the alarm is assembled, initially or later, as after complete inspection, the spider must first be slipped over the inner pipe 25,

and the two members inserted through the inspection opening in the bushing 31, the inner pipe being then screwed into the sleeve- Steam is supplied for actuating the signal as well as for testing and blowing out the accumulation of sludge. and other impurities, through a single bushing 45 (see Figs. 1 and 2 particularly). The bushing extends through and is suitably secured in the roof sheet of the boiler adjacent the alarm body. The bushing 45- has a Y-portion 46, one branch of which communicates with a tube 47 leading to a manually controlled valve 48 of any suitable construction, the body of which is secured to the float chamber body 1 as at 49. When this valve 48 is opened, as by the hand wheel 50, steam may flow from the steam space of the boiler into the float chamber.

The other branch of the Y-portion 46 leads through a pipe to a manuallycontrolled valve 56, shown in detail in Fig. 5, and which has the main body thereof formed simply to ,provide free passage from the pipe 55 through passageway 54 to a space 57 within the closure member 5 of the float chamber body. The exit from the space 57 is controlled by the float valve,in such manner as to actuate the signal, as required. The plug 60 of the valve 56 controls passage of steam from within the valve body to a bleed pipe 61. The valve 56 includes a stem 62 having a screw threaded connection 63 with the valve body and an operating wheel 64. The functions of the valve will be more fully set forth hereinafter.

The float operated signal valve, as shown, comprises a valve plug 65 slidably mounted in a sleeve 66 in the member 5 and suitably connected with upstanding extensions 67 of the float arm 3. The plug cooperates with a seat in a hollow fitting 68 which is supported'in atubular extension of the member 5 and to which the signal 7 O'is attached. The

1 signal may comprise a suitable whistle.

It will be seen from Fig. 4 that when the float is in the full line position, the valve plug 65 is seated, but when the float drops, as to the broken line position, then steam from the boiler occupying the pipe 55, valve body 56 and space 57 is admitted to the whistle, thus giving the alarm.

In order that accumulated impurities in the reservoir may be easily removed, I provide a drainage opening at 72 at the float end of the chamber and at the lowermost floor portion thereof into which opening a drain pipe 73,may be threaded, the drain pipe incorporating a hand valve 7 4 which, of course,

is normally closed but fully opened when i is desired to clean the chamber.

In operation, it will be seen that when a head of steam is generated in the boiler, the pressure thereof will force against the body of water surrounding the crown sheet and raise a column of water in the tube 6 which will overflow through the upper end of the tube into the float chamber and raise the float to substantially the position shown in full lines in Fig. 4, holding the signal valve plug 65 closed against its seat. This condition of the apparatus. remains unchanged through the normal operation of the boiler.

In the event the waterlevel recedes below the lower end of the tube 6, the water will run out of the tube and drain from the float chamber through the drain opening 21 in the bushing 21. At this point, it may be noted that whenever, due to surging of water in the boiler, as in sudden stopping of the locomotive, for example, the water may run out of the tube but there will not be time for suflicient water to run out of the float chamber through the relatively small openin 21 to cause the float to fall before the water in the boiler returns and fills up the pipe.

Hence, during such surging or temporary low water level condition, the signal will not be sounded. It is obvious that if the water level stays low, that is, below the end of the drop pipe, the float will be lowered, the valve 65 opened and the signal will continue to sound as long as there is steam in the boiler and the water supply not replenished.

It willbe understood that conditions externally of the boiler will not at any time affect the operation of the alarm, such for example, as temperature conditions; nor will the usual temperature and pressure changes in the boiler. It will be also seen that the alarm is regulatable by reason of varying the length of the drop pipe section 23 of the tube 6, so that the alarm may be given at any water level desired.

Ordinarily the alarm is cleaned of loose impurities, such aslight sludge deposits, at the same time that the alarm is tested for operation. Assuming that steam in the boiler is at boiler operating pressure and the water at the usual operating level, the alarm may be tested at any time simply by opening the valve 48, which results in an equalization of pressure between the boiler and the float chamber, thus allowing the water in the chamber to drain by gravity out of the drain hole 21, thus lowering the water level in the float chamber, allowing the float to drop and the alarm to sound. If, after the whistle starts to sound, the valve 74 of the drain line is opened then the accumulation of sludge and loose scale is removed through the drain pipe 73. Active scale accumulation is prevented in all parts of the alarm by reason of the fact that a cooler temperature prevails Within the chamber than in the boiler. The

tube 6 being within the boiler however, can be readily cleaned periodically by removing the plug 33 and thrusting a cleaning rod down the tube through the inspection opening.

Referring again to the parts associated with the signal, the main function of the valve 56 is to shut off the signal when the water in the boiler is purposely lowered, as for a general cleanout. At such time, the valve plug is withdrawn from its seat 59, the plug substantially blocking passage of steam through the passageway 54 and to the signal, and allowing steam from the pipe 55 to by-pass the signal through the bleed pipe 61, thus eliminating the annoyance of having the signal operate unnecessarily. It may be here mentioned that there is little danger of the alarm being left in inoperative condition by reason of manipulation of the valve 56 because the operator will know by reason of the emission of steam from the bleed pipe that the alarm is in such condition and will close the valve before any appreciable steam pressure is reached. It has been found that even under low pressure conditions, the escaping jet of steam is from four to six feet high and a foot in diameter, when the bleed pipe 61 is made only of one-fourth inch pipe. If the bleed pipe should be open at higher boiler pressure, the ct will be larger and more noticeable.

Summarizing the above, it will be seen that the alarm apparatus is exceedingly rugged, and practically free from the likelihood of becoming inoperable by reason of corrosion of parts and accumulation of impurities. Further, it will be seen that the various parts of the apparatus may be easily removed for thorough inspection, but may be completely cleaned without removal. The inspection opening provided by the removal of the plug 33 permits a general washout in addition to the blowout system of cleaning as well as easy inspection of the interior of the alarm. It will be seen that there is practically no likelihood of injuring the more delicate parts of the alarm during washout cleaning because of the protection afforded by the spider arrangement which prevents the insertion of a washout nozzle into the float chamber.

The provision of square threads on the plug prevents cross threading and insecure seating of the plug shoulder against the bushing 81, hence there is practically no danger of personal injury due to the plug being blown from its seat. Further, the squeeze connection between the plug and welded-in bushing is very effective in preventing steam leaks at the inspection opening, one of the inherent defects of similar arrangements heretofore used. It will be further seen that the apparatus is very compact and not subject to varying conditions surrounding the operation of the boiler, except for the one variable which is the primary source of danger, namely continued low water at the crown sheet.

I claim:

1. In a low water alarm of the type wherein there is hollow means forming a float chamber, and a float mechanism therein adapted to control a signal, in combination, tube attached to and lying within said means for admitting water to the chamber from within the boiler, a removable plug in said means, whereby the tube may be inserted into and removed from the boiler through the wall of the chamber, there being means embracing the tube and underhanging the aforesaid means and arranged to block free entrance to the interior of the chamber while permitting inspection thereof, said second mentioned means being removable on y when the tube is removed.

2. In a low water alarm, a reservoir adapted to be mounted on the wall of a boiler, a float within the reservoir, a signal, and means connecting the float with the signal whereby the float when in one position actuates the signal, a tube supported by the reservoir and having its lower end extending into the boiler and terminating substantially at the danger level of water in the boiler, a removable plug adjacent the tube and positioned in the wall of the reservoir in such manner as to permit inspection and cleaning of the tube, there being means mounted on the tube provided with spaced radial projections arranged to allow the projection of cleaning liquid into the interior of the reservoir through the opening for the plu but arranged to prevent the insertion of a hose nozzle into the reservoir during such cleaning, whereby danger of damage to the float mechanism by such nozzle is eliminated.

3. In a low water alarm for boilers, the combination of a reservoir adapted to be mounted on the boiler, a float within the reservoir, a stem passing longitudinally of the reservoir for supporting the float, a signal controlled by the float, a tube within the reservoir and passing downwardly through the roof sheet of the boiler and terminating substantially at the danger Water level, said tube having a passageway therein extending transversely of the tube and near the bottom of the float chamber for enabling Water to flow from the reservoir into the boiler, an opening in the Wall of the reservoir, and removable closure means for the opening in substantial alignment With said tube, there being means associated With the tube for preventing the entrance of a hose nozzle to the interior of the reservoir through said opening but arranged to permit the projection of cleaning fluid into the reservoir from such nozzle, whereby the float and float stem are protected against injury from the nozzle during the cleaning operation.

In testimony whereof, I hereunto afiix my signature.

FRANK M. ROBY. 

